Xref: utzoo comp.dcom.lans:996 comp.unix.wizards:6381
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From: ps@diab.UUCP (Per Erik Sundberg)
Newsgroups: comp.dcom.lans,comp.unix.wizards
Subject: Re: NFS performance: a question
Message-ID: <362@ma.diab.UUCP>
Date: 2 Feb 88 08:44:27 GMT
References: <663@noao.UUCP>
Reply-To: ps@ma.UUCP (Per Erik Sundberg)
Organization: Diab Data AB, Taby, Sweden
Lines: 20
Keywords: NFS, performance, read/write asymmetry

In article <663@noao.UUCP> brown@noao.arizona.edu (Mike Brown) writes:
>
>Why is the transfer rate when a process writes to a remote NFS file 3-4 times
>smaller than the transfer rate when reading a remote NFS file?
>
>	- Is this asymmetry a characteristic of NFS?

Yes it is. Due to the statelessnes of the NFS protocol, writes are SYNCRONOUS.
This is to make sure that the data written is on stable storage when the
client call returns. Local file writes are normally asyncronous, which will
make it possible to optimize the writes to disk using delayed writes.
BTW, early Lachman System V NFS implementations have a bug in them, that
will use async writes on the server side. Will improve performance a bit
though :-)

-- 
Per-Erik Sundberg,  Diab Data AB
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